This is the second part of The Ancients, a series of posts explaining Earth’s history; all with sarcasm and funny quips from yours truly. You should check out the first one before this one.
Quick info:
Name : Archean
Era : 4000 – 2500 m.y.a
Average Temperature: 45-70 Celsius
Atmospheric oxygen : 0%
So, after the Hadean (The eon where everything evaporated), there came the Archean. The Archean was when the first tectonic plates were created. The Earth cooled a bit, and decided that maybe, life wasn’t so bad after all. However, the temperature was still around twice or thrice what it is today. This was because of the greenhouse gases swirling in the atmosphere (like our Earth now), due to all the VOLCANIC ERUPTIONS that happened in the Hadean. Also, there was a lot of heat from the growth of the planet’s core. Oxygen still didn’t exist yet, but there were oceans, so… win-win?
Remember when I said that the Earth collided with LITERALLY EVERYTHING? Well, that kept going on in this eon. Scientists figured that out by researching on how old the Moon’s craters were. Using this information, they learnt that there were 22,000 craters with diameters of 20 KILOMETERS. 20! That’s 102 times bigger than a tennis court! Oh, and they found 40 craters with diameters bigger than 1000 km. They also found ‘several’ craters with 5000km diameters. That is one big meteor. Why did this happen? Well, the outer planets underwent ‘orbital migration’ (Which I could not for the life of me find a definition for, but I think it means their orbits shifted as they grew bigger) and basically just threw a bunch of meteors at us. Thanks a LOT! This event delayed the formation of life in the early Archean.
Notice how I said ‘delayed’. That’s right, we got life! Well, sort of. Banded iron formations – formations made of silver and iron, requires oxygen to form, and that oxygen was procured through photosynthesis, which was the only source of oxygen, actually. Life! Stromatolites existed, and they are made from mats of dead micro-organisms. More life! Primaevifilum amoenum is the oldest known bacteria, which were formed during the Archean. They were first found in Western Australia. Even more life! Lastly, Acritarcha are the remains of various organic structures-like egg casings. So. Much. LIFE! But I digress. There is much more life to come.
Shaurya Prasad (Grade 7A )